Derivatives of rifamycin sv



United States Patent 3,342,810 DERIVATIVES 0F RIFAMYCIN SV Nicola Maggi and Piero Sensi, Milan, Italy, assignors to Lepetit S.p.A., Milan, Italy No Drawing. Filed July 9, 1965, Ser. No. 470,926

Claims priority, application Great Britain, July 31, 1964, 30,327/ 64 15 Claims. (Cl. 260-2393) The present invention concerns new antibiotic substances and the process for their preparation. In US. Patent 3,150,046 the preparation of the antibiotic rifamycin by fermentation of a strain of Str. mediterrzmei ATCC 13685 is described. As stated in said patent rifamycin is a mixture of antibiotic substances. One of these substances, rifamycin B, having the crude formula C H NO is a diacid (pH 1 /2=2.8, pH 2 /2=6.7) and one of the acidic groups is a carboxyl group. One of the particular properties of this antibiotic is its increase in activity when dissolved in water, i.e. to turn into another substance having higher antibacterial activity. The more active product, called rifamycin S, has the crude formula C H NO and by mild reduction can be converted into another new antibiotic of the rifamycin class, rifamycin SV (C3I1H47N012). The process for preparing rifamycin SV comprises oxidation of rifamycin B to rifamycin O, hydrolysis of rifamycin O to rifamycin S with release of glycolic acid and reduction of rifamycin S to rifamycin SV; Both rifarnycin S and rifamycin SV lack the carboxyl group which is set free in the form of glycolic acid during the activation step.

The structure of the rifamycins has been published in 'Experientia 20, 336 (1964).

The present invention concerns new derivatives of rifamycin SV, namely, 3-formyl-rifamycin SV and its derivatives. More particularly the compounds of the in vention are 3-formyl-rifamycin SV and its derivatives of the formula wherein R represents 0, H(OH), dialkoxy, imino, substituted imino, hydrazono and substituted hydrazono radicals.

The key compound for the preparation of the above class of substances is 3-formyl-rifamycin SV, which also falls within the scope of the above generic formula. 3- formyl-rifamycin SV may be prepared starting from any of the Mannich bases of rifamycin SV, which are de-' scribed in US. patent application Serial No. 442,166, filed on Mar. 23, 1965. According to one embodiment of this invention, the selected Mannich base of rifamycin SV is oxidized to 3-formyl-rifamycin SV by reaction with a weak oxidizing agent in a solvent. The preferred oxidizing agents are alkyl nitrites and lead tetracetate, although other agents have proved useful, such as persulfates, tetrachlorohydroquinone (chloranil) and so on. The choice of the solvent depends on the nature of the selected oxidizing agent, with which it must be compatible. When the oxidation is carried out using alkyl nitrites and lead tetracetate, halogenated solvents, such as chloroform and carbon tetrachloride give excellent results. It is sometimes useful to add catalytic amounts of an aliphatic acid, such as acetic acid, to the reaction mixture, in order to speed up completion of oxidation. The reaction runs at room temperature, and is complete, depending on the selected starting compounds, after 2 to 24 hours.

The conversion of 3-formyl-rifamycin SV to its functional derivatives as defined in the generic formula above, is carried out according to well known procedures. Thus, for instance, 3-hydroxymethyl-rifamycin SV is prepared by hydrogenation of 3-formyl-rifamycin SV with NaBH.;.

The diacetals are prepared by prolonged contact of 3- formyl-rifamycin SV with a lower aliphatic alkanol at 0H CH3 CH3 l H room temperature. The compound having the group 40 -C=N- are prepare-d by reacting 3-formyl-rifarnycin OH; OH H I SV with hydroxylamine or the selected amino or hydrazino CHaOOO derivative through procedures which are well known to 0:0 0H. chemists. CH3 OH OH The new rifamycin derivatives show a high degree OH30\ 1 NH of antibacterial activity 111 vitro, as 1s apparent from the 0 8 1 following table, in which the minimal inhibitory concen- Hfi g tration in 'y/ml. against several pathogenic organi m i M 0 4 3 H= given. The symbol R is the same as in the generic formula 0 L I H above. 0-

R M. ameus S. pyog. S. jaec. B. subt. Proteus E. coli Pggitedlggt. Hmliv =0 0. 002 0. 02 0. 02 0. 02 2 2 20 10 0. 1 =NNH2 0. 02 0. 05 o. 2 0. 2 50 20 50 50 1 =N-NH-CH2 0. 05 0. 05 0. 0s 0. 1 20 10 20 50 5 =NNH-OtH5 o. 005 0. 1 o. 05 0. 05 10 5 10 20 2 =N-NHCaH4-O 0 OH-p 0. 1 1 V 1 5 100 100 100 5 =N-NH-CH2C 6115 0. 005 0. 2 0. 05 1 0. 05 5 10 10 20 0. 5

=N-NH-CHzCHgOH 0. 01 0.1 0. 05 0.1 10 10 50 50 1 =NN (01192 0. 001 0. 02 o. 01 o. 01 5 5 1o 20 0. 1

=N--N c3117 0. 002 0. 2 0. 05 0. 02 2 5 10 20 0. 05

=N-N (0.01m 0.01 1 o. 1 0. 1 100 20 100 100 0. 5

Patented Sept. 19, 1967 R M. aureus S. 191/00. S. faec. B. subt. Proteus E. coli K leb. Pseudom. H37Rv pmu. aereata Nl-T" 0. 005 0. 05 0. 02 0. 05 5 10 2O 20 5 l S =N N 0. 005 0. 05 0. 05 0. 05 10 5 10 2O 2 =N-NHC ONH2 0. 2 0. 5 1 2 100 50 100 100 5 =NNH-C|3NH2 0. 5 1 5 10 100 100 50 100 5 =N-NHS Og0 H3 0. 02 0. 05 0. 1 0. 05 100 50 50 100 1 :11 (H) 0.1 0. 2 1 1 100 50 50 50 1 =(O CH 0. 005 0. 05 0. 05 0. 05 5 2O 10 5 =NOH 0.02 0.01 O. 1 0. 1 10 5 10 5 =NO CH3 0. 0005 0. 01 0. 005 O. 01 2 5 10 10 0. 05

=N-O C Hz CH2-N O 0. 005 0. 02 0. 05 0. 2 10 5 10 20 0. 5

The new compounds of this invention have a very limited toxicity. For instance, formyl-rifamycin SV shows a LD in mice of about 400 mg./kg. intravenously and about 1500 mg./kg. by oral route. Comparable results were obtained with the other substances of this class. The experiments in vivo confirmed the excellent antibiotic properties. In tests of prevention from experimental in-'.

fection due to administration of 450 times the lethal dose of Staphylococcus aureus in mice the ED of 3-formylrifamycin SV was 4.6 mg./kg. per 0s and 2.46 mg./kg. subcutaneously. After administration of about 800 LD of S. aureus the corresponding ED for the oxime of 3-formyl-rifamycin SV was 5.66 per 0s and 2.46 subcutaneously. The derivatives with phenylhydrazine and aniline gave the following corresponding values: the former 3.03 and 2.0; the latter 1.74 and 1.15 respectively,

As an indication of the antitubercular activity, which is shared by practically all of the compounds covered by the present application, the following table gives the in vivo activity of the two derivatives in mice infected with Mycobacterium tuberculosis H37R In a first experiment mice were treated orally once a day for 30 days, starting from 2 hours after the infection and held under control for 136 days- The resultswere as follows:

Condensation product of Number Average formyl-rifamycin Dose, Number of surrate of SV with rug/kg. of mice vivals survival 4-aminomorpholine 5 10 3 110 2 10 0 3O Dimethylhydrazine 5 10 9 136 2 10 2 100 Controls 10 0 12. 5

In a second experiment controlled for 68 days, in which therapy was conducted for 43 days starting from the third day after the infection, the results were as follows:

Useful blood levels are reached by administration to humans of appropriate doses, as shown by the following table.

Blood levels average Condensation product of Number after administration formyl-rifamycin of Dose {-y/ml.)

V with subjects 2 hrs. 4 hrs. 8 hrs.

Dimethylhydraziue 12 1. 56 2. 32 1. 55 l-aminoi-methylpiperazine 8 150 3. 04 1.39 0. 46 4-aminomorpholiue 8 150 0. 04 0. 14 0. 09 1-amino-3-hydroxypi dine 4 150 0. 05 0. 28

The following are examples of preparation of the compounds covered by the present invention.

EXAMPLE 1 3-f0rmyl-rifamycin SV To a solution of 7.8 g. of 3-pyrrolidinomethyl-rifamycin SV in a mixture of 340 ml. of carbon tetrachloride and 40 ml. of acetic acid, 6g. of lead tetracetate are added, and the mixture is kept at about 20 C. for 15 hours. After pouring the mass into 500 m1. of phosphate buffer pH 7 the organic layer is separated, Washed with a 1% aqueous solution of ascorbic acid and concentrated to a volume of about 150 ml. After addition of 150 ml. of ligroin the mixture is concentrated to a small volume. The red precipitate is collected and dried. Yield 3.5 g. The product has M.P. (dec.). U.V. and visible spectrum A at 327 111;. (E

261) and 498 mu (E 141.5)

following rifamycin SV aminomethyl derivatives, which all give useful yields:

Diethylaminomethyl Dimethylarninomethyl Piperidinomethyl Morpholinomethyl 2,6-dimethylpiperidinomethyl l-methylpiperazinomethyl 4-oarboxypiperidinomethyl, and others.

Alternatively, a preparation using a nitrite as the oxidant is described to better illustrate the invention.

A mixture of 78.3 g. of 3-diethylaminomethyl-rifamycin SV, 390 ml. of carbon tetrachloride, 270 ml. of acetic acid and 1.34 ml. of isoamyl nitrite is kept at 22 C. il for 8 hours, then an additional 1.34 ml. of isoamyl nitrite is added and the mixture is kept for additional 16 hours at about 22 C. The mixture is diluted with 3800 ml. of carbon tetrachloride, washed with 3500 ml. of water containing 78 g. of ascorbic acid in solution and evaporated to dryness. The residue is recrystallized from tetrahydrofuran. Yield 31 g.

Analogous results were obtained using as the oxidizing agent either oxygen in the presence of Pd as the catalyst, or potassium ferricyanide.

EXAMPLE 2 Dimethyl hydrazone of 3-f0rmyl-ri amycin SV An amount of 0.720 g. of N,N-dimethylhydrazine (0.012 mole) dissolved in 15 ml. of tetrahydrofuran is added to a solution of 7.3 g. (0.01 mole) of formyl-rifamycin SV dissolved in 75 ml. of tetrahydrofuran, cooled in ice. After the addition the solution is allowed to stand at room temperature for 45 minutes, then concentrated to about 10 ml. The concentrate is taken up with about 150 ml. of ethyl acetate, an equal volume of ligroin is added, the mixture is concentrated to small volume, the precipitated product filtered, washed with ligroin, dried and crystallized from tetrahydrofuran. Yield 4 g. (51%) of yellow-orange crystals having M.P. 170175 (decomposition).

Analysis.Calcd. for C H N O C, 62.57; H, 6.96; N, 5.47. Found: C, 62.80; H, 7.23; N, 5.34.

U.V. and visible spectrum at pH 7.38:

X at. 335mm (E} g ,=304) and 475 mp (E} =186) EXAMPLE 3 Semicarbazone of 3-f0rmyl-rifamycin SV An amount of 7.3 g. (0.01 mole) of formyl rifamycin SV is suspended in 700 ml. of a mixture of tetrahydrofuran-water (1:1). Under cooling to 5 C. 1.20 g. (0.011 mole) of semicarbazide hydrochloride dissolved in ml. of water are added, followed by a solution of 1.8 g. of sodium acetate in 10 ml. of water. The reaction is carried out at 4 C. for hours. The solution is then concentrated to about /3 of the initial volume and extracted with ethyl acetate. The organic extract is concentrated to small volume: the yellow-orange crystals precipitated are washed with ethyl acetate and dried at C. in vacuo. Yield 3.8 g. (48%) of product melting at 175- 270" C. (decomposition).

Analysis.Calcd. for C H N O C, 59.84; H, 6.44; N, 7.16. Found: C, 60.06; H, 6.70; N, 7.30.

U.V. and visible spectrum (pH 7.38)

A at 332 my. (E{ =342.3) and 475 mp (E";' =195.1)

EXAMPLE 4 3-phenylimino-methylenev-ifamycin SV To a solution of 7.3 g. (0.01 mole) of formyl-rifamycin SV in 50 ml. of tetrahydrofuran, cooled to about 5 C. a solution of 1 ml. (0.011 mole) of freshly distilled aniline dissolved in 10 ml. of tetrahydrofuran is added portionwise. At the end of the addition the solution is kept stirred at room temperature for 3 hours, then it is concentrated to small volume and the concentrate is taken up with 60- 70 ml. of methanol. After a few minutes crystallization occurs. The crystalline precipitate of red-deep red colour is collected, washed with methanol and dried (6.6 g., yield 82%). The product, again recrystallized from MeOH shows the following characteristics: M.P. 240-245 C. (decomposition). U.V. and visible spectrum (CHCI X at, 358 mu (E{" =3l8.3) and 500 mu (E}" 151.9)

EXAMPLE 5 3-hydroxymethyl-rifamycin S V An amount of 7.3 g. (0.01 mole) of formyl-rifamycin SV is suspended in ml. of absolute ethanol. Under cooling a solution of 0.410 g. (0.04 mole) of NaBH in 25 ml. of absolute ethanol is slowly added with stirring. At the end of the addition stirring is continued for 15 minutes, then the solution is concentrated to about 20 ml. and the concentrate is taken up with about 200 ml. of ethyl acetate. The solution is extracted with phosphate buffer of pH 7.3. The organic phase is discarded. The aqueous extracts are adjusted to pH about 2 and extracted with ethyl acetate. The extract is concentrated to about 50 ml., and about 50 ml. of ligroin are then added to the mixture which is once more concentrated to about 15 ml.

The formed yellow precipitate is collected (5.8 g.) and recrystallized from ethanol. Yield 3.8 g. (52%) of product having the following characteristics: M.P. 170 C. (decomposition).

Analysis.Calcd. for C H NO C, 62.71; H, 6.69; N, 1.92. Found: C, 62.57; H, 7.08; N, 2.10.

U.V. and visible spectrum (pH 7.38)

decompose slowly above C. The U.V. and visible spectrum show maxima at 315 m (E{'' =266.4) and 450 m (E}'Zg =182.7)

EXAMPLE 7 Oxime of 3-formyl-rifamycin S V A mixture of 7.3 g. of 3-formyl-rifamycin SV, 200 ml.

v of tetrahydrofuan, 27 ml. of pyridine and 0.75 g.

of hydroxylamine hydrochloride is stirred for 3 hours at room temperature, then it is poured into about 2 'litres of ice water, made acidic with hydrochloric acid and extracted with ethyl acetate. The organic extract is concentrated to about 50 ml. and cooled. Orange crystals separate, which are collected and dried. Yield '5 .7 g. (76%); M.P. -193 C. The U.V. and visible spectrum shows maxlma at 323 m (E{" =273.9) and 468 m (E}Z" 179.4)

EXAMPLE 8 Hydrazone of 3-f0rmyl-rifamycin SV To a solution of 0.6 ml. of hydrazine hydrate in 50 ml. of tetrahydrofuran a solution of 7.3 g. of 3-formyl-rifamycin SV, in 100 ml. of tetrahydrofuran is slowly added at 5-l0 C. The mixture is concentrated to about 20 ml., diluted with a mixture of 200 ml. of ethyl acetate and 200 ml. of ligroin and concentrated to a small volume. On cooling, purpura-red crystals separate and are collected and dried. Yield 5 g. (67.5%), M.P. above 165 with de- 9 composition. The U.V. and visible spectrum shows two maxima at a 325 m (E{",,, =247.4) and 473 m (E' .=152) When the same starting compounds of this example are reacted together at higher temperatures, f.i. at the boiling point of tetrahydrofuran, a cyclization occurs with formation of a rifamycin-[4,3-c]-pyrazole, having the group 10 EXAMPLE 9 Phenylhydrazone 3-formyl-rifamycin SV Prepared by the process of Example 8 using 1.3 g. of

phenylhydrazine instead of hydrazine. Yield 4.8 g. (59% M.P. 200-205 C. (dec.); orange-yellow crystals. The U.V. and visible spectrum shows maxima at 358m;u(E{; 208.5) and 484 my (E}Z? =2()2.l)

1O EXAMPLES 10 to 43 The condensation products of formyl-rifamycin SV with a series of amines and hydrazines show the properties indicated in the following table. The process for their preparation was practically the same as indicated in the preceding examples.

M P U.V.-Spectrum Compound condensed with formyl-rifamycin SV C. 1180. 17 0 has x-(D'lll) l-aminog nid ne -270 337 304. 1 479 183. 6 4-methy1benzenesulfonylhydrazine +157 34g 22g 4 1 o-Toluidine 255+260 325 177 490 141 m-Toluidi 180+183 325 201 490 148 p-Tnluidine 170-1-175 325 169 490 p-Chloroaniline V 170-1-175 325 174. 4 490 157.4 2-amiuopyridine 270 262 417 308 208 487 174.3 4-aminopyridine 185-l-190 260 514 320 168 485 146 2-aminothimn1a 170+180 260 391 360 219 502 162.3 2-naphthylaminn 165-1-170 268 493 *360 282 500 140 4-dimethylaminoam'line 180+190 Methylhydrazine. +170 2-hydroxyethylhydrazine. -250 333 329 475 192 Benzylhydrazine 155-l-160 234 381 334 315 475 177 4carboxypheny1hydrazine -185 3g;

2 l-methyl-l-phenylhydrazine 195-1-200 233 26g 5 22 1,1-diethy1hydrazine +177 338 310. 5 478 187.8 1,1-dipropy1hydrazine 140+150 342 300.3 480 187. 4 1,1-dibuty1hydrazine. 185+190 l-aminopyrrolidine... 240+250 838+340 304.7 476+480 187. 5 l-aminopiperidin 2504-258 235 385 333 303 475 177 3-hydroxy-l-aminopiperidine 180+185 470 183 l-aminoazepine 245+260 343-1-345 320 478+480 199.3 4-aminomorpho1ine 260+267 335 321 475 186 l-amjnopiperazine 335 337 475 190 4-methy1-1-aminopiperazine 183+188 238 380 334 316 476 2,4,6tri.methy1-1-aminopiperazine 170+175 355 200.4

4 0 157 2,6-dimethyl-4-benzyl-l-aminopiperazine 150+160 3 25 200 4 5 146 4-dimethylamino-l-aminopiperidine -l60 335 304 472 171. 5 4-(l-piperidino)-l-aminopiperidine -240 273 15 .3 1-(2-dimethy1amin0ethyl)-1-methylhydrazine 192-l-195 33g 353. 2 47 170.3 4-arninntrimn1a 2404-247 230 422 262 417 338 277. 5 494 184. 2 O-methyLhydroXyla-mine 240+250 325 298 470 198 O-[2(4-morpho1ino)-et11y11-hydr0xy1amine 157-1-162 325 253.2 465-1-470 164.3

*(CHCla).

11 We claim: 1. A process for preparing a rifamycin SV derivative of the formula OH OH CH NH CH=RH OH O 0 CH3 wherein R represents oxygen, H(OH), dialkoxy, imino, substituted imino, hydrazono and substituted hydrazono radicals, which comprises subjecting to mild oxidation a 3-aminomethyl derivative of rifamycin SV of the formula CzzHatiOfi C O ?H OH OH: NH

OH2B

OH O CH:

wherein the group C H O in each formula has the structure in which R is a member selected from the group consisting of hydrogen and lower alkyl, R is a member of the class consisting of lower alkyl, hydroxy-lower alkyl, carboxy-lower alkyl and cycloalkyl groups, X is a member of the class consisting of methylene, ethylene, a group CH O and a group CH NH, R" and R' are members of the class consisting of hydrogen, lower alkyl, hydroxy and carboxy groups, with an oxidizing agent of the class consisting of lower alkyl nitrites, lead tetracetate, 1,4-quinones, persulfates, oxygen in the presence of a catalyst, potassium ferricyanide and manganese dioxide, whereby 3-formyl-rifamycin SV is obtained, and subjecting said 3-formyl-rifamycin SV,

(a) either to hydrogenation with sodium borohydride to obtain 3-hydroxymethyl-rifamycin SV,

(b) or to reaction with lower alkanols at room temperature to obtain a lower dialkyl acetal of 3-formylrifamycin SV,

(c) or to reaction with a compound selected from the class consisting of primary aliphatic, aromatic and heterocyclic amines, hydroxylamine, O-substituted hydroxylamines, hydrazine and substituted hydrazines.

2. A process for preparing formyl-rifamycin SV,

which comprises subjecting a 3-aminomethyl-rifamycin SV to mild oxidation with a oxidizing agent of the class consisting of lower alkyl nitrites, lead tetracetate, 1,4- benzoquinone, ammonium persulfate, oxygen in the presence of a catalyst, potassium ferricyanide and manganese dioxide.

3. A process for preparing 3-hydroxymethyl-rifamycin SV, which comprises hydrogenating 3-formyl-rifamycin SV with sodium borohydride in a lower alkanol at room temperature.

4. A process for preparing a di-lower alkyl acetal of 3-formyl-rifamycin SV, which comprises contacting 3- formyl-rifamycin SV with a lower alkanol at room temperature.

5. A process for preparing a 3-formyl-rifamycin SV derivative of the formula 22 aaOs OH NH CH=R 0/ 0-lo CH3 wherein the group C H O in each formula has the structure wherein R is a member of the class consisting of imino substituted imino, hydrazono and substituted hydrazono radicals, which comprises contacting 3-formyl-rifamycin SV with a compound selected from the class consisting of primary aliphatic, aromatic and heterocyclic amines, hydroxylamine, O-substituted hydroxylamines, hydrazine and substituted hydrazines.

6. A compound of the formula CH3 CH3 H on H CH3 ornooo OH H A CHZO (b) a hydrazono group of the formula /R2 =N-N 13 14 wherein R is a member of the class consisting of 11. 3-formyl-rifamycin SV semicarbazone. hydrogen and lower alkyl groups, and R is a mem- 12. 3-formy1-rifamycin SV hydrazone. ber of the class consisting of hydrogen, lower alkyl, 13. 3-formyl-rifamycin SV dimethyl acetal. hydroxy-lower alkyl, dimethylaminoethyl, p -to1y1- 14. B-hydrOXymethyI-Iifamycin SV.

sulfonyl, phenyl, p-carboxyphenyl, guanyl, carbamyl, 5 15. The aldimino derivative of 3-formy1-rifamycin SV and benzyl, and wherein R and R taken together with 4-methy1-l-aminopiperazine. with the nitrogen, form a heterocyclic ring of 5-7 atoms No references cited. 7. 3-formyl-rifamycin SV. 8. 3-forrny1-rifamycin SV dimethylhydrazone. 10 WALTER MODANCE Primary Exammer' 9. 3-formy1-rifamycin SV oxime. ROBERT T. BOND, Assistant Examiner.

10. 3-formyl-rifamycin SV methyl oxime. 

1. A PROCESS FOR PREPARING A RIFAMYCIN SV DERIVATIVE OF THE FORMULA 